Fibrous tobacco smoke filters



March 15, 1960 e. P. TOUEY FIBROUS TOBACCO SMOKE FILTERS Filed June 24,1954 FIG.1.

HYDROPH/UC NATURAL GUM PARTICLES F/L TER WRAPPER R .m H v F TOBACCO FIG.2.

CIGARETTE WRAPPER George P. Touey INVENTOR. By 7% flaw 1.

ATTORNEYS nite Stat Kodak Company, Rochester, N.Y., a carporatien at NewJersey Application lune 24, 1954, seen-N6. 439,123 8 Glaiins. Cl.131-208 The present invention relates to tobacco smoke filteri'n'gmaterial and elements thereof suitable for use in cigarettes, pipes,cigarette holders, and cigar holders. More particularly the invention isconcerned with an improvement in filters of the general type disclosedin US. Patent No. 2,701,258 to Cobb and Hargrave, and US. I atent Nos.2,794,239 and 2,794,480, to Crawford and Stevens to each of whichreference is made.

In the aforementioned applications, newly discovered advantages of acertain type of fibrous tobacco smoke filter are discussed. The proposedtype of filter is prepared from a specially conditioned tow ofsynthetically spun" continuous filaments and comprises a structurallyunitary rod-like mass of fibers and a wrapper encircling the mass,eachfiber of the mass being-substantially co extensive therewith, thefibers as a' whole beingin sub stahtial alignment longitudinally of themass but substantially each of the individual fibers having a pluralityof short portions thereof crimped into diverging" and convergingrelationship to the main fiber axis, a plurality o'fthe fibers havingsurface solvation bonds to contiguous fibersat' random points ofcontact. Very good results have been obtained in the use of such filtersfor the removal of nicotine and tars from tobacco smoke, espe-' ciallyin view of the fact that the filters supply other requirements equallyas necessary to the s'uccess'of a tobacco" smoke filter. I

Thesefiltersalso'have a markedprocessing advantageover other filtersknown in the art: However, since the fibers'in such' filters aresubstantially parallel toe'ach other, some channeling of thesnioketh'rough thefilter may be possible, resulting in a decreasedfiltering action.

In other words, while interference with the smooth flow" of combustionproducts through the channels is provided by the random bonds betweenadjacent fibers, by incompleteness of fiberorientation, andby'the'sho'rt fiber portions which arec'rimped' into' diverging and 'cdnverging? relationship to the main fiber axis, yet" a certain amount ofthe smoke in the core of" anymin'ute' column of smoke passingthrough'the filter apparently maybeexposed to somewhat less th'an atheoretically maximum amount of contact with the fiber surfacesExperimental investigations have shown that any attempt toreduce thesize of smoke channels through the filters by an increase in filterdensity either throughgreater compaction or through the use of finerfibers generallyalso results in an intolerable increase in'pressure dropthrough the filter. Unfavorable conditions also generally result when anincreased amount of fiber crimp is employed in order to increase'the:relative'number of dition of a more efficient cigarette smoke filterconsist a bundle of substantially longitudinally oriented textilejfibers infused with finely' divided hydrophilic naturat gum particles.Another object is to provide means for increasing theeific ie ncy of acigarette filter prepared from at textile fiber. A still further objectis provision of a filter which is capable of removing nicotine, tar sa'nd other deleterious components of cigarette smoke without causing thesmoke to be dry or distasteful. Another object is to increase theefiiciency of tobacco smoke fil ters of the Crawford and'Stevens patentwithout creatinga high. pressure drop. Other objects will be obviousfrom the present specification and claims. Accordingly the presentinvention consists, in general, in a tobacco smoke filtering mediumcomprising a mass of substantially longitudinally aligned fibers, thespacing of substantially all groups of adjacent fibers providing minutepassages for smoke therethrough, said mass carrying therein finelydivided hydrophilic natural gum paracles in an amount of 5 to 60% byweight of the mass, said particles occupying positions in and partiallyblocking said passages whereby a substantial portion of the smoke isimpinged either on the fibers or on the gum particle's.

A more specific embodiment of the invention comprises a new tobaccosmoke filtering material of synthetically spun continuous filamentsandan element made there from, the element comprising a structurallyunitary rodlike mass of fibers and a wrapper encircling the mass, eachfiber of the mass being substantially coextensive, therewith, the fibersas a whole being in substantial alignment longitudinally of the mass butsubstantially each of the individual fibers having a plurality of shortportions thereof crimped into diverging and converging relationship tothe main fiber axis, a plurality of the fibers having surface solvationbonds to contiguous fibers at random points of contact, the masscarrying substantially uniformly dispersed therein a solid finelydivided hydrophilic gum in the amount of 5 to 60% by weight of the mass.

Most advantageously, the invention comprises a filter of celluloseacetate fibers having surface solvation bonds achieved through theapplication of a plasticizer spray the" filter carrying uniformlydispersed hydrophilic particles in the amount of about 10 to 40% byweight of the filter. By the expression surface solvation as used hereinis meant the creation, by the action of a solvent or plasticizer and/orheat, of an adhesive, tacky or readily bonding condition of thefilaments by solution or incipient solution of surface portions of thefilament material whereby there is produced a welding and an: he'sionbetween adjacent filaments contacting at such portions, and bycoalescence is meant the" situation" caused by partial or' incipientsolvation of surface por tions of the filaments and resulting in acondition within 'those portions under which the portions will fiow into'or unite with similar'portion's of dissolved or plastic materialincontiguous filaments;

Any suitable means known to the art for spreading a .1

powder onto a fibrous surface or through a fibrous mass may be employedin preparing filters of the in-- vention. Thus, for example, the gumpowder can be blown onto the fibers or it can be" applied as a slurry ina" li'cj'uid that is not a solvent for the powder, or ina volatileorganic vehicle min a plasticizer for the fibers. Another method is toapply the gum powder to the liberselectrostatically, i.e., to induce acharge onthefi bersin the tow by friction or other suitable means andthen to run the tow in a banded, i.e., spread out'conditio n:

through a chamber containing a concentrated cloud of a ti s n-l; t u tiPowders:of t natura s m: adhere strongly to the fibers without-theaddition of 3 a binding agent, the latter may be employed if so desired.Alternatively, the surface of the fibers in the tow can be sprayed witha placticizer or glue prior to their exposure to the powder applyingdevice. In this case the plasticizer plays a dual role-theplasticization of the fibers, and the binding of the powder to thesurface of the fibers. Preferably, the gumpowder is continuously appliedto an opened and banded moving tow formed as described in the Crawfordand Stevens applications. That is to say, tow from a supply roll isopened to debundleize the filaments and provide a larger and moreuniform tow cross section, and the opened tow is spread uniformly to amuch larger width of, e.g., 8 times its original width, thereby exposingsubstantially all of the filaments to material, i.e., plasticizer,issuing from adis penser adjacent which the tow passes. The gum may beadded before, simultaneously with, or after the plasticizer, preferablywith or after.

The hydrophilic natural gum powders which are suitable in carrying outthe operation of this invention may be selected from any of thefollowing sources of natural gums:

I. Natural gums obtained from seaweed. These are represented by alginicacid, by the alginates, agar, and Irish moss.

II. Natural gums obtained from trees and, shrubs. These are representedby gum arabic, gum tragacanth, gum karaya, and the like.

III. Natural gums obtained from seed pods and legumes. These arerepresented'by locust bean gum, guar gum, and the like.

The source of the gum is not a critical factor. Rather, the form of thegum is more important. The gum should be in a highly powdered form sothat it can be slurried in a liquid or passed through a spraying nozzle.

It may be for example, 100 to 200 mesh.

The advantages of employing the natural gumsin co bination with atow ofa textile fiber to produce a cigarette filter are manifold. The majoradvantage is the fact that such powders act as an efiicient means ofpreventing channeling of the smoke through the filter. However, thefacts that the powders are non-toxic, tasteless, and odorless are alsoof considerable advantage. Being composed of polysaccharides, theypresent no danger should traces of the powders be drawn into the smokerslungs during the normal course of smoking. Another advantage is the factthat the powders are light. Thus, they can be readily blown onto thesurface of the fibers or applied as a slurry in a liquid.

The invention is illustrated in the accompanying drawings in which AFig. l is a representation of a-photomicrograph show: ing the interiorof a filter element in accordance with the invention, and

Fig. 2 is a view of a cigarette, in part cut away, which embodies afilter element of theinvention. r

The invention is further illustrated in the following examples:

Example 1 A crimped continuous filament towof yarn type cellu-'- sionrolls into a zone of relative relaxation, i.e., relatively littletension, the tow bloomed through inherent forces manifested upon thereturn of the tow to its original position.

The partially opened tow of cellulose acetate was slowly pulled over acompressed air banding device as disclosed in the aforementionedCrawford and Stevens patents and in U.S. Patent No. 2,737,688 to WallaceT. Jackson. The banding device spreads out the fibers to a width of sixinches. While the tow was in this spread condition it was sprayed withmethyl phthalyl ethyl glycollate plasticizer and passed through adusting chamber containing a highly pulverized powder of gum arabic. Onleaving the dusting chamber the tow of fibers con tained 10% plasticizerand 15% gum arabic based on the total weight of the combination.

After this spreading, spraying, and dust application treatments, the towwas uniformly collected and fed to a garniture, i.e. a cigarette-makingmachine. The tow was fed into the garniture through a shaping horn whichserved to condense the conditioned tow back into its original shape of acord; The cigarette-making machine wrapped the tow with paper and cut itinto rods similar in size to a standard size cigarette. The filter rodswere given a heat treatment for one hour at 80 C. 'to allow theplasticizer to difiuse through the fibers in the filter and impart thedesired rigidity to the rods. The rods then were readily cut into 13 mm.filter tip lengths. These tips were attached to a standard brand ofcigarettes available on the retail market in the U.S. by meansyof anadhesive tape. The cigarettes were smoked ona smoking machine similar indesign and operation to the smoking machine described by J. A. Bradford,W. R. Harlan and H. R. Hanmer in Industrial and Engineering Chemistry,vol. 28, pp. 836-9 (1936). The collected smoke was analyzed for nicotineand tars. The results of the smoking experiment were compared with thoseobtained from smoking the same brand of cigarettes containing 13 mm.filter tips made from the same tow of cellulose acetate fibersplasticized with about 10% methyl phthalyl ethyl glycollate without theaddition of hydrophilic gum.

The ten plasticized cellulose acetate tow filters com 7 taining no gumarabic allowed 130 mg. of tars and 20 lose acetate of 5 denier perfilament with a total denier of 100,000, and 9 crimps per inch was usedto prepare filters in accordance with the preliminary conditioning procedure of Crawford and Stevens. The tow was pulled from a ball warp overstationary tensioning fingers and into a tensioning device functioningto provide 'tow opening as the first phase of filament separation. Thedevice employed was'of the type employing a pair of driven rolls toplace under tension tow positon'ed in the ratch between the driven rollsand a pair of retarded rolls upstream of the driven rolls. The devicewas equipped with the improved reciprocating striker as'disc'losed andclaimed in U.S. Patent No. 2,790,208 to Smith. ,Upo n being releasedfrom the nip of the positively driven tenmg. of nicotine to passthroughinto the smoke collection flask. The ten plasticized celluloseacetate tow filters containing 15% gum arabicallowed only mg. of tarsand 14 mg. of nicotine to pass through into the smoke collection flask.

The cigarettes containing the acetate tow filter had an average pressuredrop of 27%; the cigarettes containing the filters of acetate tow andgum arabic had an average pressure drop of 29%, where pressure shop ismeasured as the percent additional time required for a standard tube ofwater to drain when the cigarette to be measured is inserted into thevent of this tube,-

compared to the draining time of the same apparatus when this vent isunobstructed with any cigarette to-be.

measured. r Example 2 The procedures described in Example 1 wererepeated using the same tow of cellulose acetate and the sameplasticizer but substituting powdered locust bean gum for the gum arabicin the dusting chamber. The plugs prepared in this case contained 78%cellulose acetate, 11%

plasticizer, and 11% powdered locust bean gum. Control plugs containingthe same types and amounts of cellulose acetate tow and plasticizer butno locust bean gum powder were also prepared in a similar manner.

' Ten 13-min. filter tips were removed from both sets of filter plugsand attached to standard cigarettes. These cigarettes were, smoked onjthe standard smoking machine and the collected smoke from each set often cigarettes was analyzedfor nicotine andtar content.

The ten plasticized cellulose acetate tow filters 0011-.

taining no locust bean powder allowed 133 mg. of tars and 19 mg. ofnicotine to pass through into the smoke collection flask. Thetenplasticized cellulose acetate tow filters containing 11% locust bean gumpowder allowed only 95 mg. of tars and 14 mg. of nicotine to passthrough into the smoke collection fiask.

The cigarettes containing the acetate tow filter had an average pressuredrop of 27%; the cigarettes containing the filters of acetate tow andlocust bean gum had an average pressure drop of 30%, where pressuredrnpis measured as explained in Example 1 above.

Example 3 The procedures described in Example 1 were repeated using thesame tow of cellulose acetate and the same plasticizer but substitutingpowdered alginic acid for the gum arabic in the dusting chamber. Theplugs prepared in this case contained 75% cellulose acetate,plasticizer, and powdered alginic acid. Ten cigarettes containing13-1'1'111'1. filter tips cut from these plugs were smoked on thesmoking machine and the collected smoke was analyzed for nicotine andtar content. Only 101 mg. of tars and 11 mg. of nicotine were found inthe smoke obtained from ten of these filtered cigarettes.

The cigarettes containing the acetate tow filter had an average pressuredrop of 27%; the cigarettes containing the filters of acetate tow andpowdered alginic acid had an average pressure drop of 28%, wherepressure drop is measured as explained in Example 1 above.

Example 4 trol plugs containing the same types and amounts of celluloseacetate tow and plasticizer but no guar gum powder were also prepared ina similar manner.

Ten 13-mmL filter tips-were removed from bothfsets of filter plugsandattached to standard cigarettes. These cigarettes were smoked on thesmoking machine and the collected smoke was analyzed for nicotine andtar content.

The ten plasticized cellulose acetate tow filters containing no powderallowed 155 mg. of tars and 21 mg. of nicotine to pass through into thesmoke collection flask. The ten plasticized cellulose acetate towfilters containing 30% powdered guar gum allowed only 105 mg. of tarsand 14 mg. of nicotine to pass through into the smoke collection flask.

The cigarettes containing the acetate tow filter had an average pressuredrop of 22%; the cigarettes containing the filters of acetate tow andguar gum had an average pressure drop of 24%, where pressure drop ismeasured as explained in Example 1 above.

.While unusually good results have been obtained with filters preparedfrom a crimped continuous filament tow of cellulose acetate fiberssprayed with a plasticizer, e.g., dimethoxyethylphthalate ormethylphthalylethylglycollate, it will be recognized by those skilled inthe art that the usefulness of the inventionextends to other fibrousfilters, including those prepared from fibers of viscose, cotton, nylon,polyamides, polyesters, etc., particularly where the fibers are insubstantial longitudinal alignment and are coextensive with the body ofthe filter.

I claim:

1. A tobacco smoke filter comprising an elongated, substantially unitarycylinder of substantially oriented, substantially coextensive, crimped,cellulose acetate filaments generally extending mainly longitudinally ofthe cylinder and providing passages for smoke therethrough,

a deposit uniformly dispersed throughout the cylinder "of W about 5%-60%by weight of solid, finely dividedhydrophilic naural gum carried on thesurfaces of filaments,

and a liquid plasticizer which serves the dual purpose of causingadherence between the filaments at random points and for causingadherence of the finely divided gum to the filaments, said filtercontaining a paper wrapper around the periphery of said cylinder.

2. A tobacco smoke filter comprising an elongated bundle of crimpedcontinuous cellulose acetate filaments wherein the continuous filamentsextend mainly longitudinally of the bundle and provide passages forsmoke therethrough, a plasticizer content on said filaments, 5 to 40% byweight of a solid -200 mesh material from the group consisting of gumarabic, gum tragacanth, gum karaya, locust bean gum, guar gum, alginicacid, alginates, agar and Irish moss carried on the surface of thefilaments, the aforesaid plasticizer serving the dual purpose of causingadherence between the filaments at random points and causing theadherence of the aforesaid solid 100-200 mesh material to the filaments,said filter containing a paper wrapper around its periphery.

3. A product in accordance with claim 2 wherein the crimped continuousfilaments have at least 9 crimps per inch.

4. A product in accordance with claim 2 wherein the References Cited inthe file of this patent UNITED STATES PATENTS 2,181,614 Streifiing Nov.28, 1939 2,190,107 Pohle Feb. 13, 1940 2,228,383 Berl Jan. 14, 19412,411,660 Manning Nov. 25, 2,459,804 Francis Jan. 25, 1949 2,476,582Browne et al. July 19, 1949 2,483,406 Francis Oct. 4,1949 2,579,984Trowbridge Dec. 25, 1951 2,688,380 MacHenry Sept. 7, 1954 2,707,308Taylor et al. May 3, 1955 2,708,175 Samfield et al. May 10, 19552,754,829 Hess Julyl7, 1956 2,774,680 Hackney et al. Dec. 18, 19562,798,850 Voightman et al. July 9, 1957 2,815,761 Shearer et al. Dec.10, 1957 FOREIGN PATENTS 121,414 Australia Mar. 30, 1944 289,058Switzerland June 16, 1953 355,002 Italy -2 Dec. 16, 1937 654,994 GreatBritain July 4,1951 665,278 Great Britain Jan. 23, 1952 682,930 GreatBritain Nov. 19, 1952 813,324 France May 31, 1937 1,081,215 France June9, 1954

1. A TOBACCO SMOKE FILTER COMPRISING AND ELONGATED, SUBSTANTIALLYUNITARY CYLINDER OF SUBSTANTIALLY ORIENTED, SUBSTANTIALLY COEXTENSIVE,CRIMPED, CELLULOSE ACETATE FILAMENTS GENERALLY EXTENDING MAINLYLONGITUDINALLY OF THE CYLINDER AND PROVIDING PASSAGES FOR SMOKETHERETHROUGH, A DEPOSIT UNIFORMLY DISPERSED THROUGHOUT THE CYLINDER OFABOUT 5%-60% BY WEIGHT OF SOLID, FINELY DIVIDED HYDROPHILIC NATURAL GUMCARRIED ON THE SURFACES OF FILAMENTS, AND A LIQUID PLASTICIZER WHICHSERVES THE DUAL PURPOSE OF CASING ADHERENCE BETWEEN THE FILAMENTS ATRANDOM POINTS AND FOR CAUSING ADHERENCE OF THE FINELY DIVIDED GUM TO THEFILAMENTS, SAID FILTER CONTAINING A PAPER WRAPPER AROUND THE PERIPHERYOF SAID CYLINDER.